That wild scene on the highway all caught on dash cam, the former new mexico state trooper who fired had is gun on a minivan full of children. Speaking out now in an abc news exclusive, the trooper was let go and now he's telling history for the first time. Abc's ryan owens is in albuquerque, for us this morning. Good morning, ryan. Reporter: Good morning, to you, robin. He is speaking out now because he wants his job back. He was fired last month after that video was made public and caused such an outrage. They are the shots heard around the world from a dash cam video that went viral. Three gunshots fired by elias montoya, the one and only time he said he fired his gun on duty in 12 years. That's you here? Yes. Reporter: That cost him his job. The minivan he shot at had a mother and five children inside. No idea when he pulled the trigger. When you found out that there were, in fact, children in that minivan, what did you think? My heart sank. I couldn't believe that there was that many children in there. Reporter: Montoya himself a father of three says all dispatch told him was to respond to an unruly driver. Get out of the vehicle right now. Reporter: He pulled up on the scene after the traffic stop had already escalated. Police say the driver, 39-year-old oriana ferrell from tennessee kept fleeing the officer who pulled her over for speeding and that her 14-year-old son scuffled with police. All I see is silhouettes of heads and what went through my mind we're outnumbered. Reporter: He said the minivan's tinted windows prevented him from seeing who was actually inside. When the driver started to flee again, the 53-year-old says he lined up with that white line on the road and shot at the tire. I'm not shooting at a human being. I'm shooting at a tire. Reporter: He missed the tire and ferrell took off again this time leading cops on a chase that reached speeds of more than 100 miles an hour. This morning, she's awaiting trial on charges of child abuse and fleeing police. She's pleaded not guilty and has since said she did what she did to protect her children. Do you want to live in a world where police officers are firing routinely at vehicles with people in them when they've been pulled over for speeding? No, and if I knew that there was even one child in that vehicle I wouldn't have done it. New mexico state police will not comment on his firing. Other than to say he violated their use of deadly force policy. Montoya says a split-second decision where no one got hurt should not cost him his career. Robin gentleman. All right, ryan, thanks to you. More on this with our chief legal affairs anchor dan abrams. What do you make of the officer's defense. One crucial detail we heard from him, which is that he is saying he heard the word "gun." Why is that so important? You're not allowed to just shoot at tires at a fleeing van. But if he heard the word "gun," he can at least argue that a reasonable police officer in his situation might have felt there was a threat to his safety. That's why that phrase is a game changer. Doesn't mean he's going to win the appeal but it means at least he's got an argument beyond i was just trying to disable the vehicle by shooting at the tires. That is's the first time we've heard any mention of the word "gun." But that being said whether or not it did, indeed, happen, the fact that he's doing the interview now, how does that play into him trying to get his job back? Look, I think he's trying to influence the appeals process. What does that mean? It's a civilian group appointed by the governor, and they are going to care about the court of public opinion and I think that he wants to get out there because currently, everyone is looking at this video and saying, how could this have happened? There's -- many people are supporting this decision. Even the governor. Even the governor of new mexico is supporting the decision. He has a lot of supporters out there. It is to "a," gal virginia thiez them but "b," present a defense so that if this civilian appeals commission does rule with him, at least there will be some level of understanding as to why that happened. Bottom line you think he can be reinstated. I think it's unlikely he'll be reinstated because of the amount of public attention and because there's a video. I think if there wasn't he'd have a shot. Okay, dan, thank you very

This transcript has been automatically generated and may not be 100% accurate.

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